Embodiments of the invention generally relate to an apparatus and a method for flowing a gas into a processing chamber. More specifically, embodiments of the invention are directed to dual directional chemical delivery systems.
In the field of semiconductor processing, flat-panel display processing or other electronic device processing, vapor deposition processes have played an important role in depositing materials on substrates. As the geometries of electronic devices continue to shrink and the density of devices continues to increase, the size and aspect ratio of the features are becoming more aggressive, e.g., feature sizes of 0.07 μm and aspect ratios of 10 or greater. Accordingly, conformal deposition of materials to form these devices is becoming increasingly important.
With the ever-increasing requirements to achieve better deposition uniformity, high productivity and low defects in atomic layer deposition and chemical vapor deposition, many chemical delivery systems have been proposed in the industry. More specifically, multi-channel systems with pump-purge capability have started to emerge in the industry due to their unique properties. The multi-channel design avoids chemical mixing before introduction to the chamber. Integrated direct pump-purge capability allows fast pumping of the channel, thus enabling higher productivity and lower defects.
However, one of the biggest challenges facing the multi-channel direct pump-purge system is the flexibility to tune deposition uniformity. Due to the long channel length, the locations where the chemical and/or purge are introduced will leave certain memory impact on the deposition uniformity. Furthermore, for the same hardware apparatus, different memory effects for different chemicals due to the differences in flow characteristics. For example, in a spiral channel design, the precursor absorption flux on the wafer shows concentration gradient corresponding to the channel length. Accordingly, there is a need in the art for showerhead designs to achieve better uniformity of precursor distribution.